Heat recovery system

ABSTRACT

The present invention is directed towards methods and systems for heating an engine, particularly during initial start-up of the engine. In one exemplary embodiment, a heat storage and release system for an engine is provided. The system may include a material capable of super cooling within an operating temperature range of the engine. The material is in thermal communication with the engine and may include an energy input device associated with the material. The energy input device may be configured to input energy to the material causing the material to undergo an exothermic phase change. During the phase change the material releases heat to the engine.

FIELD OF THE INVENTION

The invention is directed to methods and systems for heating an engine,particularly during initial start-up.

BACKGROUND

Engines often have elevated levels of exhaust emissions during initialstart-up as associated exhaust treatment devices have reached steadystate operating temperatures. As such, the efficiency of removal ortreatment of exhaust emissions is dependent upon the temperature of theengine exhaust gas and, inherently, the engine. In cooler operatingconditions engines may have increased difficulty starting or havereduced fuel economy due to lower initial operating temperatures.Existing solutions that assist engine cold starts may be costly, withrespect to necessary product and energy use, and can be cumbersome touse. Accordingly, there is a need for an improved system and method forproviding heat to an engine before or during initial start-up of theengine.

SUMMARY OF THE INVENTION

An embodiment of the invention is directed towards methods and systemsfor heating an engine, particularly during initial start-up of theengine. In one exemplary embodiment, a heat storage and release systemfor an engine is provided. The system may include a material capable ofbeing super cooled within the operating temperature range of the engine.The material is in thermal communication with the engine. In othernon-limiting examples, the system also includes an energy input deviceassociated with the material. The energy input device delivers energy tothe super cooled material sufficient to initiate an exothermic phasechange. During the phase change the material releases heat to theengine.

In another embodiment, a method of storing and releasing energy, in theform of heat, to an engine is provided. The method includes forming astructure having a cavity containing a material capable of super coolingwithin an operating temperature range of the engine and locating thestructure in thermal communication with the engine. The method alsoincludes absorbing heat generated by the engine with the material andinducing a phase change of the material from a super cooled state tothereby release the stored heat to the engine.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features, advantages and details appear, by way of example only,in the following detailed description of embodiments, the detaileddescription referring to the drawings in which:

FIG. 1 illustrates a schematic view of an engine with a heat recoverysystem of the present invention in a first mode of operation;

FIG. 2 illustrates a schematic view of an engine with the heat recoverysystem shown in FIG. 1 in a second mode of operation; and

FIG. 3 illustrates a schematic view of an engine with the heat recoverysystem shown in FIG. 1 in a third mode of operation.

DESCRIPTION OF THE EMBODIMENTS

The present invention provides methods and systems for improvingemissions, performance and efficiency of an engine during initialoperation thereof. These and other benefits are achieved through theabsorption, storage and release of potential energy, particularly heat,generated by an engine. In particular, a heat storage material capableof the absorption, storage and release of heat is provided. The materialis in thermal communication with an engine and/or a coolant flowingtherethrough. The heat storage material is configured to absorb heatgenerated by the engine during operation of the engine. Thereafter, asthe engine cools the heat storage material retains at least a portion ofthe stored energy for later release, particularly during a subsequentstart-up of the engine. When additional heat is desired for the engine,the heat storage material is caused to release the stored heat to theengine.

In one particular configuration of the heat storage material, duringoperation of the engine, the heat storage material absorbs heatgenerated by the engine causing the material to exist in a firstphysical state (e.g., liquid). The heat storage material remains supercooled in its first physical state after operation of the engine hasbeen discontinued and the engine has cooled to ambient temperatures.Prior to, or during, a subsequent start-up of the engine, the heatstorage material is caused to change to a second physical state (e.g.,solid) wherein heat is released, generally in a steady-state manner,during and after transition of the heat storage material from the supercooled liquid state to the solid state. The release of heat lowers theheating time of the engine thereby providing improved emissionreduction, performance and efficiency.

In one configuration, the heat storage material exists in a liquidphysical state at or above its melting temperature and exists in aliquid or a solid physical state at or below its freezing temperature.When the heat storage material exists as a liquid below its freezingpoint, the heat storage material is commonly referred to as being supercooled or, in a super cooled state. In this super cooled state, the heatstorage material requires additional energy to transform from a liquidstate to a solid state (i.e., cause crystallization of the heat storagematerial).

The operating temperature of the engine ranges from the cold starttemperature of the engine to a steady state operating temperature of theengine. While the cold start temperature of the engine will varyseasonally and regionally, the steady state operating temperature willbe somewhat constant. It should be appreciated that the steady stateoperating temperature may vary by engine make, model, and operatingconditions such as temperature and load. In general though, theoperating temperature of an automotive internal combustion engine isgenerally between about −40° to 129° C. As such, the heat storagematerial of the present invention is also capable of super coolingwithin that range.

Suitable heat storage materials contemplated by the present inventioninclude material capable of storing heat across the operatingtemperature range of an engine. In one exemplary embodiment, the heatstorage material is capable of existing in a super cooled state withinthe operating temperature range of the engine. Such suitable heatstorage materials include materials having a melting temperature belowthe steady state operating temperature of the engine and a freezingtemperature above a cold start temperature of the engine. Further, thesuitable materials will release heat (i.e. change phases from a supercooled liquid to a solid) at a temperature above the cold starttemperature of the engine. As such, the suitable material melts duringan operational temperature of the engine and is super cooled belowsteady state operational temperatures of the engine. When the supercooled material undergoes a phase change, the engine is heated due tothe release of heat by the heat storage material.

Specific examples of suitable heat storage materials include sodiumacetate, sodium ethanaote, disodium hydrogen phosphate dodecahydrate andthe like. In one particular configuration, the heat storage materialcomprises a sodium salt of an acetic acid, such as sodium acetate.Sodium acetate comprises a material capable of relatively easilyexisting in more than one physical state within a given temperaturerange. For example, sodium acetate has a melting temperature above about95° C. and a solidification, or freezing temperature of about 54° C.However, due to the inherent characteristics of sodium acetate, it canexist in a liquid phase at temperatures notably below 54° C., includingambient temperatures commonly encountered by engines, particularlyvehicle engines. In order to initiate solidification of super cooledliquid sodium acetate the sodium acetate must be sufficiently activatedor disturbed, such as through the energy input device. Upon disturbance,the sodium acetate changes phase from a liquid to a solid. During thisexothermic phase change, the sodium acetate heats to a temperature ofabout 54° C.

Referring to FIGS. 1-3, schematic views of an exemplary embodiment ofthe present invention are shown. In this embodiment, a heat recoverysystem 10 is provided for absorption of heat from an engine 18 and forsubsequent release of the absorbed heat to the engine. The heat recoverysystem 10 includes a structure 12 defining a cavity 14 that receives aheat storage material. The structure 12, containing heat storagematerial 16, is in thermal communication with an engine 18 and, moreparticularly, in one embodiment an engine block 20 or engine cylinderhead 25. The structure 12 containing the heat storage material 16 mayalso be in thermal communication with an engine coolant 22 flowingthrough a coolant flow path 24 defined by the engine block 20 and enginecylinder head 25.

In one exemplary operation of the heat recovery system 10, referring toFIG. 1, energy input device 26 induces an exothermic phase change in theheat storage material 16. During the phase change, referring to FIG. 2,the heat storage material 16 transforms from a first physical state(super cooled liquid) to a second physical state (solid). This phasechange results in the release of heat, by heat storage material 16,causing the engine 18 and engine coolant 22 to be heated. The additionof heat is additive to the inherent heating capabilities of the engine18 during operation. The heat generated by the engine 18 and the heatstorage material 16 is circulated through the engine block 20, viaengine coolant 22. Once the temperature of the engine 18 and enginecoolant 22 reach suitable levels, see FIG. 3, the coolant is furthercirculated through an engine cooling system 28 which may include aradiator 30 or otherwise. During this time, or at any time when thetemperature of the engine is greater than the temperature of the heatstorage material 16, the heat storage material 16 absorbs heat generatedby the engine 18. During heat absorption, the solid heat storagematerial 16 undergoes a physical phase change back to the liquid state.Upon termination of engine operation and cooling of the engine 18 toambient temperatures, the heat storage material 16 enters a supercooled, liquid state. In this state the material 16 is again ready torelease stored energy, in the form of heat, to the engine 18 uponsubsequent operation of the energy input device 26.

It should be appreciated that the engine 18 may include more than oneheat recovery system 10, each of which may function to providesimultaneous heating, sequential heating or other heating solutions. Forexample, in one configuration it is contemplated that one or more heatrecovery systems 10 may be associated with each cylinder head 25 of theengine 18. These heat recovery systems 10 may extend along all or aportion of the length or width of an engine. It should be appreciatedthat different configurations are available for obtaining a desiredheating result.

As described, the exothermic phase change of the heat storage material16 is initiated through an energy input device 26. The device may bemechanical in function and may be located inside or outside of thestructure 12 where it operates to deliver mechanical energy sufficientto initiate an the liquid to solid phase change in the heat storagematerial 16. Such mechanical energy may be in the form of wavesinitiated through percussion, vibration or otherwise. It should beappreciated that various configurations may be used for the generationof waves or other mechanical energy to the heat storage material 16. Forexample, in one configuration a moveable member maybe provided that isconfigured to strike the structure 12 containing the heat storagematerial 16 thereby transmitting energy waves through the material andinitiating a phase change therein. Such movable members may comprise apin, hammer, or other suitable percussion member and may move throughthe use of a solenoid (electrically driven, pneumatically driven orotherwise), or the like. In another configuration, the moveable memberis configured to move the structure 12 with sufficient force to causedisturbance and initiate the phase change of the heat storage material16. Other configurations are contemplated.

The energy input device 26 may be activated at different times andthrough different activation devices 32. The energy input device 26 maybe activated during an operational cycle of the engine, during anon-operational cycle of the engine, or both. In one exemplaryembodiment, the energy input device 26 is activated prior to ignition ofthe engine 18. For example, the energy input device may be associatedwith a suitable controller for activation of the energy input deviceduring approach of an operator to the vehicle, during unlocking of avehicle door, upon placement in, or rotation of, a key in an ignitionsystem of the engine 18, or otherwise. In another configuration, theenergy input device is activated during start-up of the engine. This maybe through an activation device 32 or through the natural vibration ofthe engine 18 during starting. In still another exemplary embodiment,the energy input device 26 may be activated after initial ignition ofthe engine. In configurations where more than one energy input device 26is used, it is contemplated that the energy input devices may beactivated simultaneously or at different times, such as sequentially orotherwise.

The activation device 32 may comprise any suitable device capable oftransmitting signals to the energy input device 26. In oneconfiguration, the activation device comprises a remote device, such asa remote keyless entry fob of a vehicle. In another configuration, theactivation device 32 comprises a control device associated with avehicle, such as an engine or vehicle controller. In this configuration,the controller may be in communication with the remote device, a sensorassociated with the ignition, an entry handle of the vehicle orotherwise. It should be appreciated that other configurations arecontemplated.

The heat storage material 16 is located within structure 12 that is inthermal communication with the engine 18 and optionally the enginecoolant 22 in coolant flow path 24. The structure 12 may be locatedadjacent to the coolant flow path 24 of the engine 18. In one exemplaryembodiment, the structure 12 comprises a portion of the engine 18, suchas engine block 20 or engine cylinder head 25, and the cavity 14 isdefined thereby. Hence, the structure 12 is integrally formed with theengine 18. In this configuration, the heat storage material 16 is placedwithin the cavity 14 and the cavity is subsequently sealed. In anotherconfiguration, the structure 12 is formed separately from the engineblock 18 or engine cylinder head 25 and is attached to, or otherwiseplaced in thermal communication therewith. In this configuration, theheat storage material 16 is placed in the cavity 14 and the structure 12is subsequently brought into association with the engine 18, such asplacement within an opening thereof, or mounting to (e.g., mechanicallyfastened, welded or otherwise) the engine block 20, engine cylinder head25 or otherwise. Other configurations are possible.

The quantity of heat storage material 16 located within the cavity 14 isdependent upon the quantity of heat desired for the engine 18. It shouldbe appreciated that the more heat storage material 16 placed within thecavity 14 the more potential heat is available for delivery to theengine 18. Accordingly, the quantity of heat storage material 16 may bebased upon, or proportional to, the engines size and/or heatingrequirements.

Cavity 14 may comprise any suitable shape and/or size for holding asufficient quantity of heat storage material 16. In one configuration,the cavity 14 is symmetrically shaped, such as a cylinder to facilitatemachining during production. In another configuration, the cavity 14 maybe asymmetrically shaped. This latter configuration may be particularlyadvantageous where the cavity 14 is cast into a structure comprising anengine block 20 or engine cylinder head 25 and the cavity extendsthrough all or a portion of the engine block 20, engine cylinder head25, or otherwise. As such, the heat storage material may be located atvarious locations within the engine 18 to provide desired heat transferto engine components and/or coolant. It should be appreciated that thecavity may be formed during casting of the engine block or engine heador may be subsequently machined therein.

In one detailed sequence of operation, the heat recovery system 10 isactivated by activation device 32, which operates energy input device26, prior to or during an initial start-up of the engine 18. Uponactivation the heat storage material 16 undergoes an exothermic phasechange from a super cooled, liquid state to a solid state causing arelease of heat to the engine 18. During subsequent operation of theengine, the temperature of the engine 18 and engine coolant 22 rise tolevels that exceed the melting point of the heat storage material 16thereby causing a return to a liquid phase. Once the engine is no longerin operation, the engine 18, engine coolant 22 and heat recovery system10 cool to ambient conditions. However, due to inherent propertiesdescribed, the heat storage material 16, enclosed in the structure 12,remains in a super cooled, liquid state upon cooling below its meltingpoint temperature. At this point, the heat storage material 16 can bereactivated through the energy input device 26 to again deliver heat tothe engine 18. It should be appreciated that the heat recovery system 10may be regenerated, as described, through the life of the vehiclewithout replenishment of the heat storage material 10.

While exemplary embodiments have been described and shown, it will beunderstood by those skilled in the art that various changes may be made,and equivalents may be substituted, for elements thereof withoutdeparting from the scope of the invention. In addition, manymodifications may be made to adapt a particular situation or material tothe teachings without departing from the essential scope thereof.Therefore, it is intended that the invention not be limited to theparticular embodiments disclosed as the best mode contemplated forcarrying out this invention, but that the invention will include allembodiments falling within the scope of the appended claims.

1. A heat storage and release system for an engine, comprising amaterial, capable of super cooling within an operating temperature rangeof the engine, in thermal communication with the engine; an energy inputdevice associated with the material and operable to input energy to thematerial to initiate an exothermic phase change therein and delivery ofheat to the engine.
 2. The heat storage and release system of claim 1,wherein the exothermic phase change is from a super cooled, liquid statethe to a solid state of the material.
 3. The heat storage and releasesystem of claim 2, wherein the material is further configured to absorbheat generated by the engine, to thereby undergo a phase change from thesolid state to a liquid state.
 4. The heat storage and release system ofclaim 1, wherein the exothermic phases change may be initiated beforethe operation of the engine.
 5. The heat storage and release system ofclaim 1, wherein the material comprises sodium acetate or sodiumethanaote.
 6. The heat storage and release system of claim 1, furthercomprising a structure defined by an engine for holding the material. 7.The heat storage and release system of claim 1, further comprising aseparate structure associated with an engine for holding the material.8. The heat storage and release system of claim 1, wherein the materialis in thermal communication with an engine coolant.
 9. The heat storageand release system of claim 1, wherein the energy input device comprisesa mechanical input device configured to input mechanical energy to thematerial suitable for initiating the exothermic phase change.
 10. Amethod of storing and releasing heat for an engine, comprising: placinga material, capable of super cooling within an operating temperaturerange of the engine, in thermal communication with the engine; absorbingheat generated by the engine with the material; and inducing thematerial to undergo an exothermic phase change wherein during the phasechange the material releases the absorbed heat to the engine.
 11. Themethod of claim 10, wherein the super cooled state of the material is ator below about 95° C.
 12. The method of claim 10, wherein the heatreleased by the material is about 54° F.
 14. The method of claim 10,wherein during absorption of heat by the material the material undergoesa phase change from solid to liquid, and wherein during release of heatby the material the material undergoes a phase change from a supercooled liquid, to a solid.
 15. The method of claim 10, wherein thematerial comprises sodium acetate or sodium ethanaote.
 16. The method ofclaim 10, further comprising placing the material within the engine. 17.The method of claim 10, further comprising placing the material within aseparate structure that is associated with the engine.
 18. The method ofclaim 10, wherein the phase change occurs during operation of theengine.
 19. The method of claim 10, wherein the phase change occursprior to operation of the engine.
 20. The method of claim 10, whereinrelease of heat is initiated with an energy input device, and whereinthe energy input device comprises a mechanical input device configuredto input mechanical energy to the material suitable for initiate thephase change of the material.